Question

我想创建动态布局但是当我通过addview（）method.how将控件添加到视图中时获取null poniter异常我解决了这个错误？这是我的xml文件

select_theator.xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical" >

    <LinearLayout
        android:id="@+id/linearLayout2"
        android:layout_width="100dp"
        android:layout_height="100dp" >

        <ImageView
            android:id="@+id/iv1"
            android:layout_width="115dp"
            android:layout_height="128dp"
            android:layout_alignParentLeft="true"
            android:layout_below="@+id/textView1"
            android:src="@drawable/ic_launcher" />
    </LinearLayout>

    <LinearLayout
        android:id="@+id/linearLayout1"
        android:layout_width="175dp"
        android:layout_height="175dp"
        android:layout_alignParentLeft="true"
        android:layout_alignParentRight="true"
        android:layout_below="@+id/linearLayout2"
        android:layout_marginTop="25dp" 
        android:background="@drawable/round">

        <TextView
            android:id="@+id/tvtheator"
            android:layout_width="100dp"
            android:layout_height="38dp"
            android:layout_marginTop="10dp"
            android:layout_weight="0.02"
            android:text="Copperas Cove"
            android:textColor="#000000" />

        <ImageView
            android:id="@+id/myimg"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_marginLeft="90dp"
            android:layout_marginTop="15dp"
            android:layout_weight="0.00"
            android:layout_marginRight="20dp"
            android:background="@drawable/arrow" />

    </LinearLayout>

    <Button
        android:id="@+id/seat"
        android:layout_width="match_parent"
        android:layout_height="40dp"
        android:layout_alignParentLeft="true"
        android:layout_below="@+id/linearLayout1"
        android:layout_marginTop="30dp"
        android:background="@drawable/green"
        android:text="SELECT SEATS" />

    <Button
        android:id="@+id/share"
        android:layout_width="wrap_content"
        android:layout_height="40dp"
        android:layout_alignParentLeft="true"
        android:layout_alignParentRight="true"
        android:layout_below="@+id/seat"
        android:layout_marginTop="18dp"
        android:background="@drawable/round"
        android:text="Share" />

    <RelativeLayout
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignBottom="@+id/linearLayout2"
        android:layout_alignParentRight="true"
        android:layout_marginLeft="110dp" >
    </RelativeLayout>

 <LinearLayout
     android:layout_width="200dp"
     android:layout_height="100dp"
     android:layout_above="@+id/linearLayout1"
     android:layout_alignParentRight="true"
     android:background="@drawable/gray" >

<RelativeLayout
    android:layout_width="wrap_content"
    android:layout_height="wrap_content" >

     <TextView
         android:id="@+id/tvname"
         android:layout_width="150dp"
         android:layout_height="wrap_content"
         android:textColor="#000000"
         android:text="22 JUMP STREET" />

     <TextView
         android:id="@+id/tvdate"
         android:layout_width="50dp"
         android:layout_height="34dp"
         android:layout_alignParentLeft="true"
         android:layout_alignParentRight="true"
         android:layout_below="@+id/tvname"
         android:maxLines="1"
         android:text="Thu,Jul 10th 11:05 AM" 
         android:textColor="#000000"/>

     <Button
         android:id="@+id/br"
         style="?android:attr/buttonStyleSmall"
         android:layout_width="20dp"
         android:layout_height="20dp"
         android:layout_below="@+id/tvdate"
         android:layout_centerHorizontal="true"
         android:background="@drawable/round"
         android:text="R" />

     <Button
         android:id="@+id/btime"
         style="?android:attr/buttonStyleSmall"
         android:layout_width="wrap_content"
         android:layout_height="wrap_content"
         android:layout_alignParentLeft="true"
         android:layout_below="@+id/tvdate"
         android:background="@drawable/round"
         android:text="1 hr 50 min." />

     </RelativeLayout>
 </LinearLayout>

</RelativeLayout>

这是我编辑的java文件 Theator.java

public class Theator extends Activity{
    Bitmap bitmap2;
    ImageView iv,iv1;
    TextView tv1,tv2,tv3;
    Button bt1,bt2,bt3,bt4;

    @Override
protected void onCreate(Bundle savedInstanceState) {
        // TODO Auto-generated method stub
        super.onCreate(savedInstanceState);
        ScrollView sv = new ScrollView(this);
        LinearLayout ll = new LinearLayout(this);
        ll.setOrientation(LinearLayout.VERTICAL);
        sv.addView(ll);


        setContentView(sv);
        View view = LayoutInflater.from(this).inflate(R.layout.select_theator, ll, false);
         iv = (ImageView)findViewById(R.id.iv1);
         ll.addView(iv);
          tv1=(TextView)findViewById(R.id.tvname);
          ll.addView(tv1);
          tv2=(TextView)findViewById(R.id.tvdate);
          ll.addView(tv2);
          bt1=(Button)findViewById(R.id.br);
          ll.addView(bt1);
          bt2=(Button)findViewById(R.id.btime);
          ll.addView(bt2);
         tv3=(TextView)findViewById(R.id.tvtheator);
         ll.addView(tv3);
         iv1=(ImageView)findViewById(R.id.myimg);
         ll.addView(iv1);
          bt3=(Button)findViewById(R.id.seat);
          ll.addView(bt3);
          bt4=(Button)findViewById(R.id.share);
          ll.addView(bt4);
        bitmap2 = getBitmapFromUrl("http://content7.flixster.com/movie/11/17/82/11178261_pro.jpg");
        iv=(ImageView)findViewById(R.id.iv1);
        iv.setImageBitmap(bitmap2);

    }
    private Bitmap getBitmapFromUrl(String src) {
        // TODO Auto-generated method stub
        try {

            URL url =new URL(src);
            HttpURLConnection connection = (HttpURLConnection) url.openConnection();
            connection.setDoInput(true);
            connection.connect();
            InputStream input=connection.getInputStream();
            Bitmap mybiBitmap=BitmapFactory.decodeStream(input);
            return mybiBitmap;


         } catch (Exception e) {
            // TODO: handle exception
           e.printStackTrace();
           return null;
         }


    }


}

Answer 1

iv = (ImageView)findViewById(R.id.iv1);

findViewById在当前视图层次结构中查找该视图，在您的情况下，该视图仅包含ScrollView和LinearLayout。使用inflater检索包含您要查找的ID的视图对象

View view = LayoutInflater.from(this).inflate(R.layout.select_theator, ll, false);

而不是使用

iv = (ImageView)view.findViewById(R.id.iv1);

或者您可以直接使用

View view = LayoutInflater.from(this).inflate(R.layout.select_theator, ll);

这会在ll中添加膨胀的视图，在您调用setContentView后，您可以使用findViewById，因为现在，该布局是活动视图层次结构的一部分

Answer 2

你放行

setContentView(sv);

添加完所有视图后。

想要创建动态布局但收到错误

2 个答案: